Resilient support for low-pressure mercury vapor discharge lamp



p 1956 E. w. VAN HEUVEN 2,762,9"ua

RESILIENT SUPPORT FOR LOW-PRESSURE MERCURY VAPOR DISCHARGE LAMP Filed Aug. 7, 1952 11 INVENTOR ENGELBERT WIEGMAN VAN HEUVEN BY%%WAGENT United States Patent O 'ce RESILIENT SUPPORT FOR LOW-PRESSURE MERCURY VA'POR DISCHARGE LAMP Engelbert Wiegman Van Heuven, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application August 7, 1952, Serial No. 303,07 9

Claims priority, application Netherlands September '15, 1951 1 Claim. (Cl. 240-90) It was hitherto common practice to use incandescent lamps having a particularly robust filament in lighting systems in which very heavy vibration is involved, such as marine vessels. Nevertheless, such lamps are still very vulnerable so that they frequently require replacement.

Low-pressure mercury vapour discharge tubes are also not resistant to heavy shaking when they are secured in position in the usual manner, that is to say when their ends are supported in holders or when, as suggested as an alternative, they are suspended from slack supports, for example chains. However, such a suspension, which may have advantages in the case of light vibration, is quite useless, when very heavy vibration is involved, since the tubewould tend to make intense swings and would eventually fail.

The invention is based on recognition of the fact that a low-pressure mercury vapour discharge tube is of itself less vulnerable to vibration than an incandescent lamp and that it is possible for such a tube to be supported by an attachment which does not engage the ends but which engages the tube at some distance therefrom so that mechanical stress resulting from vibration is comparatively low.

According to the invention, a low-pressure mercury vapour discharge tube is embraced by two clips rigidly secured to a base and engaging the tube at points which are spaced from the centre of the tube by a distance of not less than M; and not greater than /3 of the length of the tube. The distance of the clips from the centre of the tube is preferably a quarter of the length of the tube.

The said base is, for example, a wall of the space in which the tube is arranged or may be a separate fixture.

Such a fixture generally comprises a base having two oppositely arranged contact holders.

The contact holders by means of which the current is to be supplied to the tube may be arranged at the ends of the tube and be supported only from the tube but they are preferably arranged at the ends of resilient strip secured in position at or near the clips.

This ensures that, when sudden movement occurs in the direction of length of the tube some of this movement is transferred by the resilient strips to the contact holders, whilst at the same time it is possible for the holders to follow the movements of the ends of the tube.

In order that the invention may be clearly understood and readily carried into eifect, it will now be described in detail with reference to the accompanying drawing, in which several embodiments of the invention are shown by way of example.

Figure l is a diagram of a device in accordance with the invention and a graph of the percentage of breakage of low-pressure mercury vapour discharge tubes in accordance with the point of support and the acceleration given by a pulse of movement in a direction normal to the axis of the tube.

Figure 2 is a side view of a fixture containing a discharge tube and two contact holders,

Figure 3 is a plan view of this fixture.

Patented Sept. 11, 1956 Figure 4 is a side view of a difierent construction of such a fixture, and

Figure 5 is a plan view of the fixture shown in Figure 4.

Referring to Figure 1 a discharge tube 1 is provided with attachment clips. The clips comprise a part 2 and a part 3 which can be compressed by nuts 4 and bolts (not shown). The clips and the tube are separated by rubber rings 5. The assembly is rigidly secured to a base 6.

Plotted on the horizontal axis of the graph are the distances of the clips from the centre of the tube, expressed in parts of the length of the tube. The maximum acceleration expressed in m./sec. is plotted on the vertical axis.

Recorded are three curves, that is to say the curves A, B and C which in succession indicate percentages of breakage of 16%, 50% and 84%.

These curves show, for example, that, at an acceleration of 1200 m./Sec. 16% of the tubes break when the clips are secured to the ends. Arranging the clips at a point less distant from the centre lessens the chance of breakage.

In addition it is found that when the clips are spaced from the centre by a distance of a little over a quarter of the length of the tube only the highest accelerations are liable to result in a given percentage of breakage or in other words this point of embracement is optimum. Thus, for example, it is found that in this case 50% of the tubes will stand an acceleration of 3300 m./sec.

In addition, it is apparent from the said curves that displacement of the clips from this optimum point should preferably not be effected to a further extent than as far as A; and /3 respectively of the length of the tube, this region being designated by shadowing along the horizontal axis.

During the tests, undertaken in view thereof, the clips 2, 3 were rigidly secured to a base, the variations in length of the pulses of movement, which variations occur in the said base, being negligible. Obviously, the clips should exercise an even pressure around the tube and this requires the provision of the rubber rings 5. The effect of pulses of movement in a different direction, for example in the direction of length of the tube is not shown because such pulses are less dangerous than those acting at right angles to the tube.

Figs. 2 and 3 show a practical embodiment of the fixture for use in the device above described. The fixture comprises a base 6 made, for example, of sheet steel. The clips 2, 3 are secured to the said base. Adjacent the said clips, the base is cut open at 7 so that two tags 8 are formed to support the contact holder 9 at their ends. This construction has the advantage of enabling the holders readily to follow the movements of the tube ends.

The fixture shown in Figs. 4 and 5 is substantially identical with that just described but for the contact holders 10 being secured in braces 11 which are supported by the clips 3.

The discharge tubes to be used in this device may be of normal construction but it is preferable that the support of the electrodes should be as robust as possible. In addition, the screens or rings generally surrounding the electrodes should be supported in a highly satisfactory manner. Since these very screens or rings may be responsible for the production of faults in the tube it may be desirable for a device in accordance with the invention to comprise tubes which are not provided with screens.

What I claim is:

A device for securing a low-pressure mercury vapour discharge tube to a base and resisting forces exerted on said tube which result in accelerations of at least 1,000

m./ sec. con1pr ising two clips rigidly fixed to said base and embracing said tube at points spaced from the center of said tube by a distance of not less than /6 and not greater than /3 of the length of said discharge tube thereby maintaining said discharge tube in spaced relationship to said base, a pair of resilient contact holders engaging opposite ends of said discharge tube, a pair of resilient strips each of which is secured at one end to one of said contact holders, and a yieldable ring for each of said clips surrounding said discharge tube to thereby provide a substantially even pressure on the engaged portions of said discharge tube.

References Cited in the file of this patent UNITED STATES PATENTS Hewitt July 9, 1912 Doyle et al. Sept. 25, 1917 Koch, Jr.v May 10,1932 Marbury Dec. 26, 1933 Wiley et a1 Ian. 9; 1934 Putnam et a1 June 20,1939 A Vaughn July 18, 1950 

